US2022660A - Pump - Google Patents

Description

INVENTOR f'lqgd f: runt Patented Dec. 3, 1935 UNITED^STATES PATENT OFFICE assess rum' moya r. nini, name, msn. Appunti@ April zs, 193s, serai No. 608,02: 3 calmi (ci. 10s-ss) This invention relates to improvements in pumps for, motor vehicle fuel systems in which the pump is connected directly to a source of fuel supply and to the carbureter of the engine and is actuated by direct connection with the engine.

Pumps used in this manner are therefore subject to variable speed conditions and variable demands in fuel consumption. My present inw, vention is designed to meet the problem of y providing a continuous supply of fuelv from the fuel supply source to the carbureter with means to prevent excessive pressure being exerted on the carbureter and to prevent either overloading l 1'5 or under supply of fuel to the carbnreter.

The present invention is of the pumping type, but is arranged with a view to being very sensitive t changes in'conditions with respect to pump operation, and at the same time adapted to produce pump 'operations at the changed speed with a minimum of lag in responsiveness.`

By this means it is possible to provide for a substantial balance between the demand and sup-l ply. This is obtained through several features.

15- For instance, the pumping is made immediately responsive to t-he differences in speed of opera- 'tion of the engine and thereby immediately rsponsive to the differences in demand in the consumption of fuel, so that the change in de- 30A mand is instantly detected, and the pump* automatically responds thereto. Another feature lies in lthe fact that the pumping stroke produced by the cam action -is utilised in the delivery of the fuel to the carbureter line, thus obtaining 3g;- the beneilt of the uniformity of the cam operation; the oppositestroke is provided by a spring, thus making PGssible the conditions of a slight las with high speed conditions, but the latter does not affect the stroke length: any pulsation L eifect which might result is ineffective to vary the carbureter supply. since the spring-imparted- `stroke is `active with respect to the supply to the pump, the quantitysupplied being similar to that which would be obtained bythe cam operation,

4g. although the pumping movement may vary from the uniform timing of the cam. I

A problem present in vfuel feed pumps is provided by the condition generailyreferred to as show n in' end elevation: y

'tion of the pumping cycle:

. Fig. 2, the view illustrating the meeting the pumping of the fuel itself, the opposite stroke permitting the gas' to expand and hence not drawing the proper amount, the result being that the carbureter becomes starved for fuel.

Provision is also made for eliminating this vapor lock." by positive mechanical means and by forming the pump and locating it in such manner as to largely reduce the vaporization effect, so that, if present at all, it is of no matel0 rial detriment.

The pump, structurally, utilizes but a single diaphragm as the pumping and control element, and the assembly is such as to provide for slmplicity, rapid assembly and servicing, the arrange- 15 ment being such as to provide for a relatively low cost of manufacture, and for low service cost. including the ability to service by unskilled labor. In addition, the invention contemplates the use of a power unit which, in itself, becomes the mainn 2q servicing factor of the pump, and which can be sold independent of the Dump and capable of providing a spare for the vehicle owner capable of bodily replacement when needed.v

To these and other ends, therefore, the nature of which will be readily understood as the invention is hereinafter disclosed, said invention consists in the improved construction and combinationsoof parta-hereinafter more particularly described in detail. villustrated in the ac- V companying drawingf and more .particularly pointed out in the appended claims.-

In the accompanying drawing, in which similar reference charactersrindicate similar parts in each of the illews,.-A t 'v Figure 1 is aview illustrating dlagrammatically va fuel pumpV of the type ofthe vpresent invenf.

tion, located relative to a fuel supply tank and the carbureterto-be supplied. they pump being Fig. 2 is a sectional view, en 'online 'Z-vlof Fig. 1. and illustrating one o fv forms -which the present invention may have,- the parts being shown in the positionassumed at medial posi- Fig. 3 is aview in elevation (looking downward in Fig.' 2) ofthe present invention; and l'i'ls.l 4 is a sectionalview of the power unit of t as removedl from the pump assembly. 50.v The general conditions under which theV in-A vention is utilized are indicated in Fig. 1 in which A indicates a fuel tank and B indicates thecarbureter of a power plant such" as is usable in motor vehicley service. In the particular condi- 55 level below that of the oarbureter, so that feed of the fuel by,g'ravity fronitank to carbureter is out of the question. To meet the conditions the fuel pump C is,interposed within theconnections between/,tank and carbinete,'the connections being ,indicated as a conduit D between the tank and pump, and a conduit E between the pump and/carbureter. The present invention relates more .particular1y', .to thapumpC, and the detailed Adescription is givenof the pump unit, Fig. 1 showing the pump in end elevation.

In such arrangement, the structure may be considered as formed of two general features, one of these being the power section c, the other as a controlled fuel path section c', the m'ovement of the fuel through the latter being controlled generallyeby the needle valve of the carbureter which servesv to determine the fuel consumption per unit of time, the arrangement being such that the supply passing through thepump isdeter mined by the fuel consumption of the engine admitted to the carbureter through the usual needle valve control.

v 'I'he fuel path section is made up of a casting I 5 having the general arrangement shown in these views, the line of section being indicated in Fig. 3, the general contour' of the casting being more or less oblong, as in Fig. 1', the innerend of the casting; however, being in the form of a circular :Gange I6 which is designed to be secured to the power section as presently described. The innerendofthecastingisrecessed,asat I1to .I provide, in the assembly, the pumping chamber,

" 'l one end of this-chamber'having-a port 'I8 leading to a cavity I9 which is in communication with tiieithreadconnection 2l for conduit E. At the opposite end Vof the chamber, a small port 2l opens-into a second cavity 22. Cavities Il and 22 are completedv respectively by threaded mem'- bers 23fand 24, inserted' from the outer side of the casting. Member 2 2 is a' closure for cavity Il, and carries a. post 22a for positioning a light coil spring 25 designed to urge avalve '2i to its seat 511 'at -the outlet end of port Il. Member 24, hows ever, is provided with a port 24a leading to cavity 22, the inner end of the member forming a valve seat' for avalve 21 normally urged to such seat bya light' coil spring 24 surrounding a ,post 29 of the casting.

. Cavitiesj I9 and 22 are separated by a wide web structure III which .is preferably formed with a. through opening or channel II to permit of the free' .passage of air therethrough, the'opening ing designed as a part of thegeneral arrangeentf'for retaining-the'pump @ooi in order to obviate the conditions of vaporlockkI TheAv outer end lof the casting is recessed and arranged with a seat toreceiife a filtering screen 32, held in place by a cap '22 formed to'constitute a sump, the cap being secured in position by suitable'securingmeans, this'being shown asa bolt 34 threadedio theweb structure 2l andprojecting'V throughthe cap, the --outerend of lthe `bolt being threaded to receive a nut 2i. The inturned ila'ng'e of thus provides a recess on the outerv side of.` screen 22, the recesses on opposite sides of the screen th providing ample space for. the-movement of the fuel through the. mfiltering structure. Cap-23 is provided with nthe threaded opening 23a to which the conduit D is As will be understood; the fuel enters through opening) 22a, passes -the screen- 22, and then throughport 24a into cavity 22 i'rom where it passes througlyport 2| into the pump chamber I1. When' pumped from the latter the fuel passes through port I8 into cavity I9 and then onward to the carbureter. Valve 21 controls the admission of fuel to cavity 22, while valve 26 5 controls the discharge of fuel from chamber Il, these valves being of suitable structure and generally of thin sheet metal so as to provide for .light weight and aid in the sensitive operation of theapparatus..- i, 10 f VThe pumping chamber vI1 is completed by a flexible diaphragm 21 of suitable material, this diaphragm being peripherally secured between flange I6 and a similar ange 38a carried by cylindrical housing 38, the diaphragm thus form- 15 amovable inner wall of the chamber, Nand being considered as a part oi the power section c.v

The. movements of the cam f of the cam shaft F are madevactive upon a disk or `follower 40 located within housing 38, through an actuator, 20 the disk'being operatively-connectedwith the diaphragm. by a coil spring. of. suitable small power value-two Vor three pounds, for instance. To take care of wear conditions and to provide true movement of the diaphragm, the latter, at 25 its center, carries a pair of clampingmembers 43 mounted on opposite sides ofthe diaphragm, spring 4I contacting with the inner member-,42, Stem 42 secured to the diaphragm clamping Vmembers extends through a central .opening in the ,o disk 4II, and carries a stop structure inthe form of a collar. There .is no connection between the stem in either the disk owne actuator, sotnat relative movement between. the stem anddisk is possibleatallttimes. The actuator may diier somewhat in its form as shown in the present embodiment of my inveny` tion. ln Fig. 2, thehousing 28 carries'a tubular extension" 38h withinwhicnislocateda tubular member 45, closed at its innerjend, the opposite 40 end contacting with disk 40. Member 45 has its closed end contacting with cam -f and thus serves asanractuator for positively moving the disk 40 in ,the direction-of the diaphragm. The actuator member `45 receives'the projecting:endof the stem 42 freely, thus permitting'relative movement. therebetween. In this form, ther-pump is rdesig'ned to besecured .to' the sidewall G 0f the crank case of an -internal combustion engin 'with-the extension 38h. extending into the crank 50 casein proximity to the cam shaft. so that the cam f acts vdirectly on-'the actuator without' any open communication between :the pump and the crank case..

To move disk 42 'in the opposite -directilonjto u maintain the pistoni on the' cam= and"toprovidc the suction stroke to the diaphragm, there` is a spring 5B of suiilcientipowerto provide the desired action,- and necessarily ,of greater ypower than spring 4|. Spring' il lies 'between'the disk .0 and a suitable abutment structure, and surrounds spring 4I, so thatboth springs 4I and Il are located on the same side of the disktheside op; posite the actuator.

The abutment -is in the formof'aspider Il iiav-` ing an annular securing iiange $8 `which is adapted to be clamped,I with the diaphraamf-between the flanges IB and 24a -`This arrangement makes possible, the productionof what ima! be termed a powerunit--sho'wnasremavedn Figi ia-capable of bodily `insertionfaiid'removal from the powersection, by simply 'separating'the nous-'- ing andcasing. Since the 'parts whichvf'orm lthis unit comprise practically all of the pants which are likely to deteriorate in use, it can fbe 'readily 1| quire the services of an expert, so that service costs are greatly reduced. The drain opening 58 is provided to allow the oil that may seep into the pump from the crankcase to' escape.

The operationl of the pump will be readily understood. Movement of the diaphragm towards and away from the pumping chamber serves to contract and expand the pumping chamber and thereby set up a pumping action therein to draw fuel fromwthe fuel source and Y expel it from the pump to the carbureter. However, there are certain characteristics present, due to the arrangement of the power section by which the supply and demand are accurately balanced.

The disk 4U, in effect, provides the power source for the movement of the diaphragm. The disk, however, is connected with the diaphragm only on its compression stroke through the coil spring 4| which, as pointed out above, is of but a few pounds pressure. The engine actuated stroke of the diaphragm, therefore, is a cushioned stroke. On the suction stroke, the disk is connected with the diaphragm only through the power spring 50 and the collar 44 and the stem 42, leaving the lighter spring 4I to follow the disk by the force of its own expansion. At idling speeds,` the pressure exerted on the liquid fuel will be approximately that of the spring 4| and, that pressure together with the reduced speed of the engine and,.of necessity, the consequent reduction in frequency of the pumping impulses, will be found toI be suf-- iicient to supply the carbureter of the engine with an adequate amount of fuel. With the increase in the speed of operation of the engine, there will be an increased demand for fuel that must be supplied without an increase in the effective pres'- sure on the carbureter. the resultant of several factors. One is the reduction in the effective vpressure of the actuating mechanism on thediaphragm by reason of the loss of energy in the spring 4I due to its inability to follow the disk as the speed of operation increases or, in other words, the time interval required for the spring to expand Land follow the disk is greater than the time interval between the compression impulses imparted to the @lik by the actuator. Another is the increase in e frequency of the pumping impulses due Ato the increased speed of the actuating mechanism.

By providing disk 40 as the active power member for the diaphragm, several advantages are present. The opposing power sourcesf---the actuator and spring Aill-operate directly upon the same element, so that the disk 40 is thus moved spring 50 to be located on vthe opposite side of the member from the actuator, and on the same side as the idling spring 4|, thus not only providing for a compact arrangement aswell as the production of a power unit such as indicated in Fig. 4, but in addition, permits of an advantageous use of the direct actuator stroke.

The diaphragm movements in the direction of pumping into'cavity I9, shouldgbe as uniform as it is possible to provide them. ls''his can be done ,by utilizing the cam and actuator as the power source during this stroke, thus utilizing the regularity of the cam f for the purpose, so that a sameness in stroke as well as a certainty in the i timing of the stroke is assured, since there is no 75 possibility of lag present. Spring 5I, being a 'Ihis is accomplished by'.

In addition, it permits power source only, and eective on disk 40, can be giv'en a desired power value, sufficient for instance, to maintain the actuator in contact with the cam. It is possible, however, that conditions may be present, during motor operation, when changes in speed, etc., might. create a tendency to a slight lag-of no material effect in maintaining substantial contact of actuator and cam, since the power would immediately compensate-a condi- -tion which might become effective on the diaphragm movements to vary slightly from a regularity such as is provided by the cam. The final result would not be changed, since the increased rapidity ofmovement of the disk on the return stroke would be effective to decrease the pressure of the pumping chamber sufiiciently to cause the iiow of fuel into the pumping chamber in the proper amount even though in a shorter period. Such variations in diaphragm action are immaterial on the suction stroke, since the time of .supply does not affect the operation, whereas a variation in the timing during the pumping stroke could tend to set up a somewhat pulsating action inthe supply line to the carbureter.

The strokes of the disk 40 will be equal in length in each case, but the timing factor may differ because of the use of a spring as the power source for one of the strokes. Because of this condition, it is obviously advantageous that the actuator power stroke be utilized for the pumping stroke to avoid, as far as possible, the production of pulsating activities in conduit E, any pulsating leiect in conduit D due to this source, be- -ing unimportant.

The arrangement thus provides for two independent power sources of similar stroke length characteristic and which are in opposition relative to the disk 40, so that the strokes of the latter are of equal length, with the timing of the strokes provided by the `cam movements. The power sources cli-operate in producing the `stroke length, since spring 50 is effective in subvthe carbureter, and at the same time ensures that a proper quantity of fuel will be delivered to the pumping chamber from thesupply.

' And by utilizing spring 4| as the connection between the disk 40 and the diaphragm, it is possible to utilize the difference in pressure between the diaphragm and the disk at low speeds and at high -speeds to determine the effective pressure .on the discharge line without affecting the stroke-length of the disk, and at the sametime meet the conditions due to the sudden changes in the-demand `for fuel, should that demand occur when the disk 40 is out of its position at the inner end of its stroke. Consequently, the pump is exceedingly sensitive in action and at the same time is sturdy and capable of sustaining the service conditions required, re-

If the diiiiculty is with the springs of the powerA section or 4the diaphragm, the casting and housing vare separated by removal of the securing screws, and, with the unit of Fig. 4 employed, a

lspare unit placed in position and the sections united. It either of the valve springs are affected, a removal of nut permits the pump to be removed and affords access to the'removable members 23 and 24.. The oost of the unit of Fig. 4 is small as compared with the cost of the pump, so that not only is the cost of expert assistance avoided, but the cost of the substitution is itself relatively small.

The present structure in addition to lproviding a novel and effective fuel pump is designed to effectively meet the problem of vapor lock both by positive mechanical means and by structural design. The movable disk 40 is reclprocated back and forth rapidly and acts vas an air agitator in close proximity to ythe fuel path and in combination with the housing Ilv and the openings 54 in the securing flange 38a constitutes an air impeller that will draw in and expel air to and from the housing and thereby maintain a low temperature at the point in the fuel path where vapor lock" is most likely to occur. Without the use.of the housing I8 the movable disk 40 will agitate the air in proximity to the diaphragm sothat the excessiveheat developed in operation will not effect the fuel in the pump and will adequately prevent the formation vof vapor lock. If desired openings I8 may be provided in the housing.

The present structure is designed so that, where it is in contact with the crank case, communication between the interior of the pump and the interior of the crank case is closed and the heated gases therein are prevented from ready access to the interior of the pump and this is accomplished by the use of the tubular piston 45 as the pumping actuator. Hence, the heat condition of themotor is reduced to this extent. By reason of the particular mechanical structure employed inthe power unit, it is also made possible to space the valve casing through whch the fuel passes away from the crank case,- the distance of the space occupied by the actuating mechanism and the power unit and this distance will be found to position the valve casing out from the crank case of the engine to where it will be in a current of `airpassng. through the hood of the automobile. Provisionis also made in the'` valve casing I5 between the fuel passages vfor free access to external air by the open johannel 3l which ventilates and keeps this particuylar section cool and thus eliminates heating of the valve casing as a source of vapor lock. To enable this to be done, the web 30 is provided in the casting I5 and in order to screen the fuel and have the web-30 the fuel inlet port is placed in the cap 33, instead of in the side wall of the valve casing.

'As will be understood, the general arrangement is relatively simplenand-of comparatively low cost of manufacture and of maintenance. The arrangement is such that the pump can be installed to meet various types of motor vehicle structures, the fuel section being substantially the same, in s each case, the cap structure permitting of a top or side supply connection, while the power section can be actuated in any suitable manner. Consequently, the production costs vfor supplying various types are retained at aminimum, while providing 1o for the general similarity in action and for emcient service.

What I claim isz- 1. An actuating means for a diaphragm type fuel pump comprising an engine operated cam, a l5', rigid actuator in contact with said cam, a spring positioned between the diaphragm and said actuator and in direct contact with said diaphragm forl actuation of said diaphragm on its compression stroke under the inuence ,of said cam, a pull rod 2i) secured to said diaphragm and extending axially` of said spring, said pull rod terminating in an enlarged head which resides internally of said actuator, a fixed abutment immediately adjacent the diaphragm and comprising a spider through 'which the diaphragm actuating spring is posi-- 2. An operating unit for diaphragm pumps harv- 8 .5'

ing a fuel'path casing and pump operating mech'- anism comprising: a diaphragm adapted to form a closure for' the fuel path casing,'a rod rigidly secured at one end to the diaphragm and having an enlarged head at its other end, a plate rigidly 4o secured to the rod at the end which is attached to the diaphragm, asupporting member and a plate loosely surrounding said rod,*the inner diameter of the supporting member being less than the outer diameter of `the nxed plate, a relatively Q." strong spring surrounding the rod and reacting between said supporting member and said loose plate and urging said supporting member against the fixed plate and the loo plate into contact with the rod head, a relatively weak spring sur- 6 0- rounding the rod and reacting at one end against the fixed plate and at its other end against the loose plate, and a power actuator for said loose plate.

3. An operating unit as in claim 2, the support- I,

fing member and the diaphragm being in periph-

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